Surfactant as titanation ligand

ABSTRACT

A method comprising contacting a silica support with a titanium-containing solution to form a titanated silica support, wherein the titanium-containing solution comprises a titanium compound, a solvent, and a surfactant.

TECHNICAL FIELD

The present disclosure relates to catalyst compositions. Morespecifically, the present disclosure relates to methods of preparingolefin polymerization catalyst compositions and polymers prepared fromsame.

BACKGROUND

An economically important class of olefin polymerization catalystsincludes chromium-silica-titanium (Cr/Si—Ti) catalysts prepared fromsilica-based catalyst supports. Rigorous drying of the water-sensitivecatalyst components used to produce Cr/Si—Ti catalysts increases thetime and cost of production. Development of an aqueous solution suitablefor depositing titanium onto a silica-based catalyst support wouldreduce the costs of production of olefin polymerization catalysts. Thus,there is an ongoing need to develop new methods of producing olefinpolymerization catalysts.

SUMMARY

Disclosed herein is a method comprising contacting a silica support witha titanium-containing solution to form a titanated silica support,wherein the titanium-containing solution comprises a titanium compound,a solvent, and a surfactant.

While the subject matter disclosed herein is susceptible to variousmodifications and alternative forms, only a few specific aspects havebeen shown by way of example and are described below in detail. Thedetailed descriptions of these specific aspects are not intended tolimit the breadth or scope of the subject matter disclosed or theappended claims in any manner. Rather, the detailed written descriptionsare provided to illustrate the present disclosure to a person skilled inthe art and to enable such person to make and use the concepts disclosedherein.

DETAILED DESCRIPTION

The present disclosure encompasses olefin polymerization catalysts andpre-catalyst compositions thereof, methods of preparing olefinpolymerization catalysts and pre-catalyst compositions thereof, andmethods of utilizing olefin polymerization catalysts. In an aspect, amethod of the present disclosure comprises contacting a silica supportor a chromium-silica support (i.e., support) with titanium to produce aCr/Si—Ti catalyst. The methodologies disclosed herein contemplate theuse of a titanium-containing solution (e.g., an aqueous titaniumsolution (ATS)) to facilitate the association of titanium with thesupport (e.g., in the presence of water). In an aspect, a methodologyfor preparation of the olefin polymerization catalyst comprisescontacting a chromium-silica support with the titanium-containingsolution (e.g., ATS) under conditions suitable to form a pre-catalystcomposition and further processing the pre-catalyst composition toproduce a Cr/Si—Ti catalyst. In an alternative aspect, a methodology forpreparation of the olefin polymerization catalyst comprises contacting(e.g., simultaneously or sequentially) a silica support with thetitanium-containing solution and a chromium-containing compound (e.g.,an ATS further comprising a chromium-containing compound) underconditions suitable to form a pre-catalyst composition and furtherprocessing the pre-catalyst composition to produce a Cr/Si—Ti catalyst.While these aspects may be disclosed under a particular heading, theheading does not limit the disclosure found therein. Additionally, thevarious aspects disclosed herein can be combined in any manner.

It has been surprisingly discovered that surfactants can be utilized asligands for titanium (e.g., via addition of one or more surfactants tothe titanium-containing solution (e.g., ATS), and that the surfactantsaid in effective titanation of the silica support. Although non-ionicsurfactants can be particularly effective, cationic and anionicsurfactants can also work as ligands for titanium according to thisdisclosure.

Aspects of the present disclosure are directed to catalyst compositionsand pre-catalyst compositions. In an aspect, a catalyst compositioncomprises an olefin polymerization catalyst (e.g., a Cr/Si—Ti catalyst).In a further aspect, the olefin polymerization catalyst comprises atreated pre-catalyst composition. In yet a further aspect, the treatedpre-catalyst composition comprises a pre-catalyst composition that hasbeen subjected to an activation treatment (e.g., calcination, optionallysubsequent to drying) as disclosed herein.

Disclosed herein are methods of making pre-catalyst compositions andpre-catalyst compositions made thereby. In an aspect, a method of makinga pre-catalyst composition in accordance with the present disclosurecomprises: forming a titanated silica support via contact of a silicasupport (e.g., a silica support or a chrominated silica support) with antitanium-containing solution (e.g., ATS) formed by dissolving atitanium-containing compound (also referred to herein as a “titaniumcompound”) in a solvent (e.g., an aqueous solution to yield an ATS)comprising a surfactant and optionally a carboxylate, wherein thecarboxylate (when present) comprises a multi-carboxylate, analpha-hydroxy carboxylate, or a combination thereof; drying thetitanated support to form a dried titanated support; and adding chromiumby (a) using a chrominated silica support as a starting material, (b)adding a chromium-containing compound to the titanium-containingsolution (e.g., ATS), and/or (c) contacting (i) the silica support, (ii)the titanated silica support, (iii) the dried titanated support, or (iv)a combination thereof with a chromium-containing compound (also referredto herein as a “chromium compound”) to form the pre-catalystcomposition. In aspects (for example, where the titanium precipitatesupon contact of the titanium-containing compound with water), thetitanium-containing solution can further comprise a carboxylatecomprising a multi-carboxylate, an alpha-hydroxy carboxylate, or acombination thereof to aid in dissolving the solid titanium. Thepre-catalyst composition may be further processed (e.g., dried andcalcined) to form a catalyst (e.g., a Cr/Si—Ti catalyst).

In an aspect, a method of forming a pre-catalyst composition or catalystin accordance with the present disclosure comprises contacting a silicasupport (e.g., a silica support or a chrominated silica support) with anaqueous titanium solution (ATS) formed by dissolving a titanium compoundin an aqueous solution comprising a surfactant. In aspects (for example,where the titanium precipitates upon contact of the titanium-containingcompound with water), the ATS can further comprise a carboxylatecomprising a multi-carboxylate, an alpha-hydroxy carboxylate, or acombination thereof to aid in dissolving the solid titanium. In aspects,the ATS further comprises a chromium-containing compound. Thepre-catalyst composition may be further processed (e.g., dried andcalcined) to form a catalyst (e.g., a Cr/Si—Ti catalyst).

In an aspect, a method in accordance with the present disclosurecomprises contacting a silica support with a titanium-containingsolution to form a titanated silica support, wherein thetitanium-containing solution comprises a titanium compound, achromium-containing compound, a solvent, optionally a carboxylate (e.g.,a multi carboxylate, an alpha-hydroxy carboxylate, or a combinationthereof), and a surfactant, wherein the silica support is selected fromthe group consisting of a silica xerogel (e.g., a dried silica xerogel),a silica hydrogel (e.g., a dried silica hydrogel), solid silica (e.g.,crystalline silicon dioxide), solid silica-alumina, and combinationsthereof. The method can further comprise drying the titanated silicasupport (e.g., by heating the titanated silica support to a temperaturein a range of from about 50° C. to about 200° C. and maintaining thetemperature of the titanated silica support in the range of from about50° C. to about 200° C. for a time period of from about 30 minutes toabout 6 hours) to form a pre-catalyst composition. The method mayfurther comprise calcining the pre-catalyst (e.g., by heating thepre-catalyst in a reducing atmosphere to a temperature in a range offrom about 400° C. to about 1000° C. and maintaining the temperature ofthe pre-catalyst in the range of from about 400° C. to about 1000° C.for a time period of from about 1 minute to about 24 hours) to form acatalyst (e.g., a Cr/Si—Ti catalyst suitable for olefin polymerization).

In an aspect, a method in accordance with the present disclosurecomprises contacting a chrominated silica support with a aqueoustitanium solution to form a titanated, chrominated silica support,wherein the aqueous titanium solution comprises water, a titaniumcompound, optionally a carboxylic acid, and a surfactant; drying thechrominated, titanated silica support (e.g., by heating the chrominated,titanated silica support to a temperature in a range of from about 50°C. to about 200° C. and maintaining the temperature of the chrominated,titanated silica support in the range of from about 50° C. to about 200°C. for a time period of from about 30 minutes to about 6 hours) to forma pre-catalyst; and calcining the pre-catalyst (e.g., by heating thepre-catalyst in a reducing atmosphere (e.g., in the presence of oxygen)to a temperature in a range of from about 400° C. to about 1000° C. andmaintaining the temperature of the pre-catalyst in the range of fromabout 400° C. to about 1000° C. for a time period of from about 1 minuteto about 24 hours) to form a catalyst. In an aspect, the aqueoustitanium solution can be prepared by (i) preparing a first solution bycombining the carboxylic acid (e.g., oxalic acid) and water; (ii) addingthe titanium compound (e.g., titanium isopropoxide) to the firstsolution to form a second solution, and (iii) adding the surfactant tothe second solution to form the aqueous titanium solution.

In an aspect, a method in accordance with the present disclosurecomprises contacting a silica support with a aqueous titanium solutionto form a titanated, chrominated silica support, wherein the aqueoustitanium solution comprises water, a titanium compound, achromium-containing compound, optionally a carboxylic acid, and asurfactant; drying the chrominated, titanated silica support (e.g., byheating the chrominated, titanated silica support to a temperature in arange of from about 50° C. to about 200° C. and maintaining thetemperature of the chrominated, titanated silica support in the range offrom about 50° C. to about 200° C. for a time period of from about 30minutes to about 6 hours) to form a pre-catalyst; and calcining thepre-catalyst (e.g., by heating the pre-catalyst in a reducing atmosphere(e.g., in the presence of oxygen) to a temperature in a range of fromabout 400° C. to about 1000° C. and maintaining the temperature of thepre-catalyst in the range of from about 400° C. to about 1000° C. for atime period of from about 1 minute to about 24 hours) to form acatalyst. In an aspect, the aqueous titanium solution can be prepared bycontacting the components thereof in any order (e.g., simultaneously orsequentially). In an aspect, the aqueous titanium solution can beprepared by (i) preparing a first solution by combining the carboxylicacid (e.g., oxalic acid) and water; (ii) adding the titanium compound(e.g., titanium isopropoxide) and the chromium-containing compound tothe first solution to form a second solution, and (iii) adding thesurfactant to the second solution to form the aqueous titanium solution.

The source of titanium to be incorporated into the titanium-containingsolution (e.g., an ATS) may be any titanium compound capable ofproviding a sufficient amount of titanium to the olefin polymerizationcatalyst and the pre-catalyst composition thereof. In a further aspect,the titanium-containing compound comprises a tetravalent titanium(Ti(IV)) compound or a trivalent titanium (Ti(III)) compound. The Ti(IV)compound may be any compound that comprises Ti(IV); alternatively, theTi(IV) compound may be any compound that is able to release a Ti(IV)species upon dissolving into the solvent to form the titanium-containingsolution (e.g., ATS). The Ti(III) compound may be any compound thatcomprises Ti(III); alternatively, the Ti(III) compound may be anycompound that is able to release a Ti(III) species upon dissolving intothe solvent to form the titanium-containing solution (e.g., ATS). In anaspect the titanium compound is a Ti(IV) compound that hydrolyzes uponcontact with an aqueous solution to yield hydrated titania (e.g., asfreshly precipitated titania in the aqueous solution that can be furtherdissolved by inclusion of a carboxylate (e.g., carboxylic acid) in theaqueous solution as shown in the Examples below). In an aspect thetitanium compound is a Ti(IV) compound that hydrolyzes upon contact withan aqueous solution to yield hydrated titania is a titanium alkoxide.

In an aspect, the titanium-containing compound suitable for use in thetitanium-containing solution (e.g., ATS) of the present disclosurecomprises a titanium alkoxide. In aspects, the titanium-containingcompound comprises a Ti(IV) compound comprising at least one alkoxidegroup; or alternatively, at least two alkoxide groups. Ti(IV) compoundssuitable for use in the present disclosure include, but are not limitedto, Ti(IV) compounds that have the general formula Ti(OR)₄, TiO(OR)₂,Ti(OR)₂(acac)₂, Ti(OR)₂(oxal), or a combination thereof, wherein each Ris independently ethyl, isopropyl, n-propyl, isobutyl, or n-butyl;“acac” is acetylacetonate; and “oxal” is oxalate. Alternatively, thetitanium-containing compound comprises a titanium(IV) alkoxide. In anaspect, the titanium(IV) alkoxide can be titanium(IV) ethoxide,titanium(IV) isopropoxide, titanium(IV) n-propoxide, titanium(IV)n-butoxide, titanium(IV) 2-ethylhexoxide, or a combination thereof. In aparticular aspect, the titanium-containing compound can be titanium(IV)isopropoxide.

In an aspect, the titanium-containing compound suitable for use in thetitanium-containing solution (e.g., ATS) of the present disclosurecomprises a Ti salt such as oxylate, lactate, citrate, glycolate,tartrate, etc.

In a still further aspect, the titanium-containing compound suitable foruse in the present disclosure can comprise hydrous titania, titaniumhydroxide, titanium dioxide, titanic acid, titanyl sulfate, titaniumacetylacetonate, titanium oxyacetylacetonate, or a combination thereof.

In yet another aspect, the titanium-containing compound suitable for usein the present disclosure can comprise a titanium(IV) halide,non-limiting examples of which include titanium tetrachloride, titaniumtetrabromide, titanium(IV) oxychloride, and titanium(IV) oxybromide. Ina further aspect the titanium(IV) halide can comprise a titaniumalkoxyhalide having the general formula Ti(OR)_(n)Q_(4-n); wherein eachR independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl;wherein Q may be a fluoride, a chloride, a bromide, an iodide, or acombination thereof and wherein n may be an integer from 1 to 4.

In aspects, the titanium compound can be formed in situ in the aqueoustitanium solution. For example, in aspects, forming an aqueous titaniumsolution comprising a titanium compound having the formulaTi(acac)₂(OR)₂ comprises in situ formation of the titanium compoundhaving the formula Ti(acac)₂(OR)₂ by the combination of acetylacetone(acac) and a titanium precursor having the formula Ti(OR)₄ duringformation of the aqueous titanium solution.

In an aspect, the titanium compound has the formula Ti(OR)₄, TiO(OR)₂,Ti(OR)₂(acac)₂, or Ti(OR)₂(oxal), wherein “acac” is acetylacetonate,“oxal” is oxalate, and each R independently is ethyl, isopropyl,n-propyl, isobutyl, or n-butyl. In an aspect, the titanium compound is atitanium (IV) compound selected from the group consisting of Ti(OH)₄,TiO(OH)₂, TiO₂, TiO(oxalate)₂, and combinations thereof, or a titanium(III) compound selected from the group consisting of Ti₂(SO₄)₃,Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, and combinations thereof.

An amount of titanium present in an olefin polymerization catalyst ofthe present disclosure may range from about 0.01 wt. % to about 10 wt.%; alternatively, from about 0.5 wt. % to about 5 wt. %; alternatively,from about 1 wt. % to about 4 wt. %; or alternatively, from about 2 wt.% to about 4 wt. % titanium based upon the total weight of the olefinpolymerization catalyst. In another aspect, the amount of titaniumpresent in the olefin polymerization catalyst may range from about 1 wt.% to about 5 wt. % titanium based upon the total weight of the olefinpolymerization catalyst. Herein, a titanium percentage refers to aweight percent (wt. %) of titanium associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination). In a further aspect, an amount oftitanium present in a pre-catalyst composition of the present disclosuremay range from about 0.01 wt. % to about 25 wt. %; alternatively, fromabout 0.1 wt. % to about 20 wt. %; alternatively, from about 0.5 wt. %to about 10 wt. %; alternatively, from about 1 wt. % to about 6 wt. %;or alternatively, from about 2 wt. % to about 4 wt. % titanium basedupon a total weight of silica within the pre-catalyst. Herein, atitanium percentage refers to a weight percent (wt. %) of titaniumassociated with the pre-catalyst composition based upon a total weightof silica within the pre-catalyst composition after completion of allprocessing steps excluding activation via calcination.

The titanium-containing solution (e.g., aqueous titanium solution (ATS))of this disclosure further comprises a surfactant. Surfactants (alsoreferred to as surface active agents) suitable for use in the presentdisclosure are compounds that lower the surface tension (or interfacialtension) between two liquids, between a gas and a liquid, or between aliquid and a solid. Surfactants are usually organic compounds that areamphiphilic, meaning they contain both one or more hydrophobic groups(e.g., tails) and one or more hydrophilic groups (e.g., heads).Therefore, a surfactant contains both a water-insoluble (or oil-soluble)component and a water-soluble component. In an aspect, thesurface-active molecule is partly hydrophilic (water-soluble) and partlylipophilic (soluble in lipids, or oils). The “tails” of most surfactantsare fairly similar, consisting of a hydrocarbon chain, which can bebranched, linear, or aromatic. Most commonly, surfactants are classifiedaccording to polar head group. A non-ionic surfactant has no chargedgroups in its head. An ionic surfactant carries a net positive ornegative charge in its head. If the charge is negative, the surfactantis more specifically called anionic. If the charge is positive, thesurfactant is more specifically called cationic. A zwitterionic oramphoteric surfactant contains a head with two oppositely chargedgroups. In an aspect, the surfactant comprises a non-ionic surfactant,an anionic surfactant, a cationic surfactant, a zwitterionic surfactant,or a combination thereof. In an aspect, the surfactant comprises anon-ionic surfactant, a cationic surfactant, or a combination thereof.

In aspects, the surfactant comprises a non-ionic surfactant, a cationicsurfactant, an anionic surfactant, or a combination thereof. In aspects,the surfactant comprises a non-ionic surfactant. In aspects, thesurfactant comprises a cationic surfactant. In aspects, the surfactantcomprises an anionic surfactant. In aspects, the surfactant comprises anon-ionic surfactant, a cationic surfactant, or a combination thereof.In aspects, the titanium-containing solution (e.g., ATS) comprises fromabout 1% to about 25%, from about 2% to about 20%, or from about 5% toabout 15% of the surfactant, based on weight of the surfactant and theweight of the titanium solution. Alternatively, the amount of surfactantused in the titanium-containing solution (e.g., ATS) can be from about2% to about 50%, from about 4% to about 40%, or from about 10% to about30% of the surfactant, based on weight of the silica. In aspects, thetitanium-containing solution (e.g., ATS) comprises from about 0.5% toabout 15%, from about 1% to about 10%, or from about 3% to about 10% ofthe surfactant, based on weight of the surfactant and the weight of thetitanium.

In a further aspect, the surfactant may be any surfactant suitable foras a titanation ligand as disclosed herein. Non-limiting examples ofsurfactants suitable for use in the present disclosure include nonionicsurfactants, ionic surfactants, amphoteric surfactants, or combinationsthereof. In an aspect, the surfactant may be a nonionic surfactant. In afurther aspect, the surfactant comprises one or more functional groupsincluding but not limited to alkoxylates, polyalkoxylates, ethoxylates,polyethoxylates, glucosides, sulfates, sulfonates, disulfonates,phosphate esters, sulfosuccinates, quaternary ammonium salts, betaines,or combinations thereof. In yet a further aspect, the surfactant may bea nonionic surfactant comprising one or more functional groups includingpolyalkoxylates, polyethoxylates, or glucosides; alternatively,polyalkoxylates; alternatively, polyethoxylates; alternatively,glucosides; or combinations thereof. In a particular aspect, thesurfactant may be a nonionic surfactant comprising a polyethoxylatedalcohol, a polyethoxylated mercaptan, or a combination thereofalternatively, a polyethoxylated alcohol; or alternatively, apolyethoxylated mercaptan.

In aspects, the surfactant comprises one or more or alkyl, aryl, oralkylaryl sulfates; sulfonates or phosphates of alkali metals, or thecorresponding ammonium salts. Suitable surfactants also can comprisealkylsulfonic acids, sulfosuccinate salts, fatty acid salts, ethoxylatedalcohols, amphiphilic copolymers, or combinations thereof.

In a still further aspect, the surfactant may comprise one or more ofthe following: 1-Oleoyl-rac-glycerol, Brij® 58, Brij® L23, Brij® L4,Brij® 010, CYMAL-2®, CYMAL-5®, CYMAL-6®, Decaethylene glycol monododecylether, Decyl β-D-glucopyranoside, Decyl β-D-maltopyranoside,Deoxy-BigCHAP, Digitonin, ECOSURF™ EH-9, ECOSURF™ SA-9, Genapol® X-100,Igepal® CA-630, Igepal® CA-720, Kolliphor® P 188, Kolliphor® P 407,Kolliphor® EL, MEGA-8, MEGA-9, MEGA-10, Methoxypolyethylene glycol,N,N-Dimethyldodecylamine N-oxide, n-Dodecyl β-D-maltoside, n-Heptylβ-D-thioglucopyranoside, n-Hexadecyl β-D-maltoside,n-Nonyl-β-D-Glucopyranoside, n-Nonyl-β-D-maltoside,n-Octyl-β-D-maltoside, n-Octyl-β-D-thioglucopyranoside,n-Octyl-b-D-Glucopyranoside, Nonaethylene glycol monododecyl ether,Nonidet™ P40 Substitute, Nonylphenyl-polyethyleneglycol acetate,Octaethylene glycol monododecyl ether, PLURONIC® 25 R-2, PLURONIC® 10R-5, PLURONIC® F-127, PLURONIC® F-68, Poloxamer 407, Poly(ethyleneglycol), Polyoxyethylene (10) tridecyl ether, Polyoxyethylene (40)stearate, Polysorbate 20, Polysorbate 60, Polysorbate 80, Saponin, Span®20, Span® 40, Span® 60, Span® 80, Span® 85, Sucrose monolaurate,Synperonic® PE/P84, SURFYNOL® 61, SURFYNOL® 465, SURFYNOL® 2502,TERGITOL™, TERGITOL™ NP-7, TERGITOL™ NP-9, TERGITOL™ NP-10, TERGITOL™NP-40, TERGITOL™ 15-S-7, TERGITOL™ 15-S-9, TERGITOL™ 15-S-30, TERGITOL™15-S-40, TERGITOL™ TMN 6, TERGITOL™ TMN 10, TERGITOL™ TMN-100X,Tetraethylene glycol monododecyl ether, Tetramethylammonium hydroxidepentahydrate, Thesit®, TRITON™ X-100, TRITON™ X-114, TRITON™ X-165,TRITON™ X-305, TRITON™ X-405, TRITON™ X-405, TRITON™ X-705,TRITON™-CG-110, TWEEN® 20, TWEEN® 40, TWEEN® 60, TWEEN® 65, TWEEN® 80,TWEEN® 85, Tyloxapol, and Undecyl-β-D-maltoside, all of which areavailable commercially from MilliporeSigma, and AQUA-CLEEN®availablecommercially from Chemical Products Industries, Inc. In a particularaspect the surfactant can comprise TERGITOL® 15-S-7 or AQUA-CLEEN®.

In some embodiments, the titanium-containing solution (e.g., aqueoustitanium solution (ATS)) of this disclosure further comprises acarboxylate. In aspects, the titanium-containing solution comprises amono-carboxylate, a multi-carboxylate, an alpha-hydroxy carboxylate, aβ-hydroxycarboxylates, an α-ketocarboxylate, or a combination thereof.In aspects, an aqueous titanium solution is produced via inclusion of acarboxylic acid. The carboxylic acid can comprise a monocarboxylic acid,a dicarboxylic acid, a tricarboxylic acid, an α-hydroxycarboxylic acid,a β-hydroxycarboxylic acid, an α-ketocarboxylic acid, or a combinationthereof. In an aspect, the carboxylic acid may be a C₁ to C₁₅monocarboxylic acid or a C₁ to C₅ monocarboxylic acid; alternatively, aC₁ to C₁₅ dicarboxylic acid or a C₁ to C₅ dicarboxylic acid;alternatively, a C₁ to C₁₅ tricarboxylic acid or a C₁ to C₅tricarboxylic acid; alternatively, a C₁ to C₁₅ α-hydroxycarboxylic acidor a C₁ to C₅ α-hydroxycarboxylic acid; alternatively, a C₁ to C₁₅β-hydroxycarboxylic acid or a C₁ to C₅ β-hydroxycarboxylic acid; oralternatively, a C₁ to C₁₅ α-ketocarboxylic acid or a C₁ to C₅α-ketocarboxylic acid; or a combination thereof. As utilized herein,multi-carboxylic includes carboxylic acids comprising two or morecarboxylic acid groups.

In a particular aspect, the titanium-containing solution comprises acarboxylic acid selected from the group consisting of acetic acid,formic acid, citric acid, gluconic acid, glycolic acid, glyoxylic acid,lactic acid, malic acid, malonic acid, oxalic acid, propionic acid,phosphonoacetic acid, tartaric acid, and combinations thereof. In yet afurther aspect, the titanium-containing solution comprises oxalic acid.In yet a further aspect, the titanium-containing solution comprisesmalonic acid.

In aspects, the titanium-containing solution (e.g., aqueous titaniumsolution (ATS)) comprises an equivalent molar ratio of the carboxylicacid to the titanium compound in a range of from about 1 to about 4,from about 1.5 to about 3, or from about 1.8 to about 2.5, oralternatively greater than or equal to about 1, 2, 3, or 4. In aspects,the titanium-containing solution (e.g., aqueous titanium solution (ATS))comprises an acidic equivalent ratio of the carboxylic acid to thetitanium compound in a range of from about 2 to about 12, from about 3to about 10, or from about 4 to about 8.

In an aspect, the titanium-containing solution of the present disclosurecomprises a solvent. The solvent may be an aqueous solvent, an alcohol,a ketone, or a combination thereof. In an aspect, the solvent compriseswater and the resultant solution is an aqueous titanium solution (ATS).A non-limiting example of an aqueous solvent suitable for use in thepresent disclosure comprises deionized water, distilled water, filteredwater, or a combination thereof. Non-limiting examples of alcoholssuitable for use as the solvent include methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol, pentanol, hexanol, cyclohexanol,heptanol, octanol, benzyl alcohol, phenol, or a combination thereof.Examples of ketones include acetone, 2-pentanone, 3-hexanone, and thelike.

The ATS can be formed by combining the titanium compound, thecarboxylate(s) (when present), the surfactant(s), and the solvent in anysuitable order (e.g., simultaneous or sequentially) known to one ofskill in the art and with the help of this disclosure. In a particularaspect, an a titanium-containing solution (e.g., ATS) as disclosedherein comprises an aqueous ligand mixture that may be prepared bycontacting a carboxylate (e.g., carboxylic acid) as described herein andthe solvent (e.g., water) to form acid aqueous solution, followed byaddition of a titanium compound, followed by addition of a surfactant.In aspects, water, a titanium compound and a carboxylate are combined toform a first solution, and a small amount of surfactant, as describedhereinabove, is added to the first solution to form an ATS. In anaspect, the titanium compound, the carboxylate(s), the surfactant(s),and the solvent (e.g., water) can be contacted simultaneously to formthe titanium-containing solution (e.g., ATS). In an alternative aspect,the titanium-containing compound, the carboxylate(s), and thesurfactant(s) may be contacted and subsequently contacted with thesolvent (e.g., water) to form the titanium-containing solution (e.g.,ATS) as disclosed herein. In a further aspect, the titanium compound canbe dissolved in one or both of the carboxylate(s) and the surfactant(s);and solvent (e.g., water) added thereto.

In aspects, the titanium-containing solution consists essentially of orconsists of the titanium compound, the carboxylate(s), thesurfactant(s), and the solvent. In aspects, the aqueous titaniumsolution (ATS) consists essentially of or consists of the titaniumcompound, the carboxylate(s), the surfactant(s), and water.

In a particular aspect, the aqueous titanium solution (ATS) suitable foruse in the present disclosure may be characterized by a pH of less thanabout 5.5. Alternatively, the ATS may be characterized by a pH in arange of from about 2.5 to about 5.5; alternatively, from about 3.0 toabout 5.0; or alternatively, from about 3.5 to about 4.5.

The titanium-containing solution (e.g., ATS) comprises titaniumdissolved therein, such that an olefin polymerization catalyst and apre-catalyst composition thereof of the present disclosure comprisetitanium. The titanium can be incorporated into the pre-catalystcomposition or the catalyst by contacting a silica support with thetitanium solution-containing (e.g., ATS).

In an aspect, the titanium-containing solution (e.g., ATS) comprisestitanium and chromium dissolved therein, such that an olefinpolymerization catalyst and a pre-catalyst composition thereof of thepresent disclosure comprise titanium and chromium. The titanium andchromium can be incorporated into the pre-catalyst composition or thecatalyst by contacting a silica support with the titaniumsolution-containing (e.g., ATS) that further comprises one or morechromium-containing compounds of the type disclosed herein. The ATSfurther comprising chromium can be formed by combining the titaniumcompound, the carboxylate(s) (when present), the surfactant(s), thechromium-containing compound, and the solvent in any suitable order(e.g., simultaneous or sequentially) known to one of skill in the artand with the help of this disclosure. In a particular aspect, an atitanium-containing solution (e.g., ATS) as disclosed herein comprisesan aqueous ligand mixture that may be prepared by contacting acarboxylate (e.g., carboxylic acid) as described herein and the solvent(e.g., water) to form acid aqueous solution, followed by addition of atitanium compound and a chromium-containing compound, followed byaddition of a surfactant. In aspects, water, a titanium compound, achromium-containing compound, and a carboxylate are combined to form afirst solution, and a small amount of surfactant, as describedhereinabove, is added to the first solution to form an ATS. In anaspect, the titanium compound, the chromium-containing compound, thecarboxylate(s), the surfactant(s), and the solvent (e.g., water) can becontacted simultaneously to form the titanium-containing solution (e.g.,ATS). In an alternative aspect, the titanium-containing compound, thechromium-containing compound, the carboxylate(s), and the surfactant(s)may be contacted and subsequently contacted with the solvent (e.g.,water) to form the titanium-containing solution (e.g., ATS) as disclosedherein. In a further aspect, the titanium compound and thechromium-containing compound can be dissolved in one or both of thecarboxylate(s) and the surfactant(s); and solvent (e.g., water) addedthereto. In aspects, the titanium-containing solution consistsessentially of or consists of the titanium compound, thechromium-containing compound, the carboxylate(s), the surfactant(s), andthe solvent. In aspects, the aqueous titanium solution (ATS) consistsessentially of or consists of the titanium compound, thechromium-containing compound, the carboxylate(s), the surfactant(s), andwater.

Thus, a catalyst (e.g., a Cr/Si—Ti olefin polymerization catalyst) and apre-catalyst composition thereof of the present disclosure comprise asupport material that comprises silica (i.e., silicon dioxide, SiO₂),which is referred to herein a silica support. The silica supportprovides a solid substrate that provides physical/structural support forthe catalytic metals (e.g., Cr and Ti) of the pre-catalyst compositionand the resultant catalyst (e.g., olefin polymerization catalyst). Thesilica support may be any silica support suitable for preparation of theolefin polymerization catalyst and the pre-catalyst composition thereofas disclosed herein. The silica support may be a naturally occurringmaterial comprising silica or a synthetic material comprising silica.The silica support may be prepared using any suitable method, e.g., thesilica support may be prepared by hydrolyzing tetrachlorosilane (SiCl₄)with water or by contacting sodium silicate and a mineral acid. In aparticular aspect, the silica support may be a produced by a gelmanufacturing process (e.g., a sol-gel process), which may provide ahydrogel silica support or a xerogel silica support. Silica supportsproduced via gel manufacturing processes can be dried prior to contactwith any other catalyst components (e.g., drying a hydrogel to form axerogel).

The silica support suitable for use in the present disclosure maycontain greater than about 50 wt. % silica; alternatively, greater thanabout 80 wt. % silica; or alternatively, greater than about 95 wt. %silica based upon the total weight of the silica support. In an aspect,the silica support comprises an amount of silica in a range of fromabout 70 wt. % to about 95 wt. % based upon a total weight of the silicasupport.

The silica support may include additional components that do notadversely affect the catalyst, such as zirconia, alumina, thoria,magnesia, fluoride, sulfate, phosphate, or a combination thereof. In aparticular aspect, the silica support of the present disclosurecomprises alumina, and may be referred to as a silica-alumina support(i.e., a SiO₂/Al₂O₃ support).

Non-limiting examples of silica supports suitable for use in thisdisclosure include ES70, which is a silica support material with asurface area of 300 m²/gram and a pore volume of 1.6 cm³/gram, that iscommercially available from PQ Corporation; V398400, which is a silicasupport material that is commercially available from Evonik; and theSYLOPOL® family of silica supports commercially available from W. R.Grace & Co.

The silica support suitable for use in the present disclosure may have asurface area and a pore volume effective to provide for the productionof an active olefin polymerization catalyst. In an aspect of the presentdisclosure, the silica support possesses a surface area in a range offrom about 100 m²/gram to about 1000 m²/gram; alternatively, from about250 m²/gram to about 1000 m²/gram; alternatively, from about 250 m²/gramto about 700 m²/gram; alternatively, from about 250 m²/gram to about 600m²/gram; or alternatively, greater than about 250 m²/gram. The silicasupport may be porous and further characterized by a pore volume ofgreater than about 0.9 cm³/gram; alternatively, greater than about 1.0cm³/gram; or alternatively, greater than about 1.5 cm³/gram. In anaspect of the present disclosure, the silica support is characterized bya pore volume in a range of from about 1.0 cm³/gram to about 2.5cm³/gram. The silica support may be further characterized by an averageparticle size in a range of from about 10 microns to about 500 microns;alternatively, about 25 microns to about 300 microns; or alternatively,about 40 microns to about 150 microns. Generally, an average pore sizeof the silica support may be in a range of from about 10 Angstroms (Å)to about 1000 Angstroms (Å). In one aspect of the present disclosure,the average pore size of the silica support is in a range of from about50 Angstroms (Å) to about 500 Angstroms (Å); alternatively, from about75 Angstroms (Å) to about 350 Angstroms (Å).

The silica support may be present in the olefin polymerization catalystand a pre-catalyst composition thereof in an amount in a range of fromabout 50 wt. % to about 99 wt. %; or alternatively, from about 80 wt. %to about 99 wt. %. Herein a silica support percentage refers to a weightpercent (wt. %) of the silica support associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination). Alternatively, the silica supportpercentage refers to a weight percent (wt. %) of the silica supportassociated with the pre-catalyst based upon the total weight of thepre-catalyst after completion of all relevant processing steps excludingactivation via calcination.

In an aspect, preparation the catalyst (e.g., a Cr/Si—Ti olefinpolymerization catalyst) and the pre-catalyst composition thereofexcludes thermal treatment (e.g., drying) of the silica support prior tocontact with any other catalyst component (e.g., prior to contact withthe titanium-containing solution (e.g., ATS) and/or prior to contactwith a chromium-containing compound). In an embodiment where the silicasupport is a xerogel silica support, the xerogel is not subjected toadditional drying after formation of the xerogel (e.g., after formation,a xerogel silica support may absorb some ambient moisture which is notremoved by further drying prior to contact with any other catalystcomponent). Consequently, the silica support suitable for use in thepresent disclosure may be a termed a hydrated silica support. Withoutwishing to be limited by theory, the hydrated silica support comprises asilica support wherein water evolution occurs when the silica support isheated within a range of from about 180° C. to about 200° C. undervacuum conditions for a period of time ranging from about 8 hours toabout 20 hours. In a further aspect, the silica support may contain fromabout 0.1 wt. % to about 20 wt. % water; alternatively, about 1 wt. % toabout 20 wt. % water; alternatively, about 1 wt. % to about 10 wt. %water; or alternatively, about 0.1 wt. % to about 10 wt. % water basedupon the total weight of the silica support.

In alternative aspects, the silica support may be a dried silicasupport, and the method of making the pre-catalyst composition canfurther comprise drying a hydrated silica support to provide the driedsilica support, and the dried silica support can be subsequentlycontacted with one or more additional catalyst components (e.g.,contacted with the titanium-containing solution (e.g., ATS) and/orcontacted with a chromium-containing compound). The silica support canbe dried, for example, by heating the silica support to a temperature ina range of from about 150° C. to about 250° C. and maintaining thetemperature of the silica support in the range of from about 150° C. toabout 250° C. for a time period of from about 1 hour to about 24 hoursto form the dried support.

In a particular aspect of the present disclosure, a silica supportsuitable for use in the present disclosure comprises chromium. Thesilica support comprising chromium may be termed a chrominated silicasupport or a chromium-silica support (Cr—Si support or Cr-silicasupport). In another aspect, the chrominated support comprises thecharacteristics disclosed herein for the silica support whileadditionally containing chromium. A non-limiting example of thechrominated silica support is HA30W, which is a chromium-silica supportmaterial that is commercially available from W. R. Grace and Company. Inother aspects, a method of forming a pre-catalyst composition orcatalyst of this disclosure can further comprise contacting the silicasupport with a chromium-containing compound to form a chrominated silicasupport, and the chrominated silica support can be contacted with atitanium-containing solution (e.g., ATS) of the type disclosed herein.

In a still further aspect, an olefin polymerization catalyst and/or apre-catalyst composition thereof of the present disclosure compriseschromium. In such aspects, chromium can be incorporated into thepre-catalyst composition or the catalyst via the contacting of thesilica support, the titanated support, the dried titanated support, or acombination thereof with a chromium-containing compound to form thepre-catalyst composition, which can be calcined to form thepolymerization catalyst. In an aspect, one or more chromium-containingcompounds are added to the titanium-containing solution (e.g., ATS), andchromium and titanium are added concurrently to the silica support bycontact with the titanium-containing solution (e.g., ATS) that furthercomprises chromium. The source of chromium may be anychromium-containing compound capable of providing a sufficient amount ofchromium to the olefin polymerization catalyst and the pre-catalystthereof. In an aspect, the chromium-containing compound may be awater-soluble chromium compound or a hydrocarbon-soluble chromiumcompound, and the silica support may be contacted with an aqueouschromium-containing solution (e.g., an ATS further comprising achromium-containing compound) or a hydrocarbon chromium-containingsolution. Examples of water-soluble chromium compounds include chromiumtrioxide, chromium acetate, chromium nitrate, or a combination thereof.Examples of hydrocarbon-soluble chromium compounds include tertiarybutyl chromate, biscyclopentadienyl chromium(II), chromium(III)acetylacetonate, or a combination thereof. In one aspect of the presentdisclosure, the chromium-containing compound may be a chromium(II)compound, a chromium(III) compound, or a combination thereof. Suitablechromium(III) compounds include, but are not limited to, chromium(III)carboxylates, chromium(III) naphthenates, chromium(III) halides,chromium(III) sulfates, chromium(III) nitrates, chromium(III) dionates,or a combination thereof. Specific chromium(III) compounds include, butare not limited to, chromium(III) sulfate, chromium(III) chloride,chromium(III) nitrate, chromium(III) bromide, chromium(III)acetylacetonate, and chromium(III) acetate. Suitable chromium(II)compounds include, but are not limited to, chromium(II) chloride,chromium(II) bromide, chromium(II) iodide, chromium(II) sulfate,chromium(II) acetate, or a combination thereof.

An amount of chromium present in the olefin polymerization catalyst maybe in a range of from about 0.01 wt. % to about 10 wt. %; alternatively,from about 0.5 wt. % to about 5 wt. %; alternatively, from about 1 wt. %to about 4 wt. %; or alternatively, from about 2 wt. % to about 4 wt. %chromium based upon the total weight of the olefin polymerizationcatalyst. In another aspect, the amount of chromium present in theolefin polymerization catalyst may be in a range of from about 1 wt. %to about 5 wt. % chromium based upon the total weight of the olefinpolymerization catalyst. Herein, a chromium percentage refers to aweight percent (wt. %) of chromium associated with the olefinpolymerization catalyst based upon the total weight of the olefinpolymerization catalyst after completion of all processing steps (i.e.,after activation via calcination). In a further aspect, an amount ofchromium present in a pre-catalyst composition may be in a range of fromabout 0.01 wt. % to about 10 wt. %; alternatively, from about 0.1 wt. %to about 5 wt. %; alternatively, from about 0.2 wt. % to about 2 wt. %;or alternatively, from about 0.5 wt. % to about 1.5 wt. % chromium basedupon a total weight of silica within the pre-catalyst composition.Herein, a chromium percentage refers to a weight percent (wt. %) ofchromium associated with the pre-catalyst composition based upon thetotal weight of silica within the pre-catalyst composition aftercompletion of all processing steps excluding activation via calcination.

In aspects of the present disclosure the pre-catalyst compositioncomponents or catalyst components disclosed herein may be contacted inany order or fashion deemed suitable to one of ordinary skill in the artwith the aid of the present disclosure to produce, respectively, apre-catalyst composition or an olefin polymerization catalyst having thecharacteristics disclosed herein.

In aspects, forming the titanated support further comprises contacting asilica support with the titanium-containing solution (e.g., ATS) to formthe titanated support, which can be dried to form a dried titanatedsupport. In such aspects, the silica support (e.g., a hydrated or driedsilica support), the titanated support, the dried titanated support, ora combination thereof can be contacted with the chromium-containingcompound and dried to form the pre-catalyst composition. In otheraspects, forming the titanated support further comprises contacting aCr-silica support with the titanium-containing solution (e.g., ATS) toform a chrominated, titanated support that can be dried to for thepre-catalyst and calcined to form the catalyst.

In a particular aspect, a method of forming a pre-catalyst compositioncomprises forming a titanated silica support by contacting a chrominatedsilica support (e.g., a hydrated or dried chrominated silica support)with the aqueous titanium solution (ATS), as described herein, to form atitanated, chrominated support; and drying the titanated, chrominatedsupport to form the pre-catalyst composition, which can be calcined toform the catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition comprises forming a titanated, chrominated silica support bycontacting a silica support (e.g., a hydrated or dried silica support)with the aqueous titanium solution (ATS) that further comprises achromium-containing compound, as described herein, to form a titanated,chrominated support; and drying the titanated, chrominated support toform the pre-catalyst composition, which can be calcined to form thecatalyst.

In another particular aspect, a method of forming a pre-catalystcomposition comprises forming a titanated silica support by contacting asilica support (e.g., a hydrated or dried silica support, as describedherein) with the aqueous titanium solution (ATS), as described herein,to form a titanated support; contacting the titanated support with thechromium-containing compound to form a chrominated, titanated support,and drying the chrominated, titanated support to form the pre-catalystcomposition, which can be calcined to form the catalyst.

In another particular aspect, a method of forming a pre-catalystcomposition comprises forming a titanated silica support by contacting asilica support (e.g., a hydrated or dried silica support) with theaqueous titanium solution (ATS), as described herein, to form atitanated support; drying the titanated support to form the driedtitanated support; and contacting the dried titanated support with thechromium-containing compound to form chrominated, titanated support, anddrying the chrominated, titanated support to form the pre-catalystcomposition, which can be calcined to form the catalyst.

In an aspect, contacting of the silica support (e.g., the hydratedsilica support, the dried silica support) or the chrominated silicasupport with the titanium-containing solution (e.g., ATS) can beeffected by any suitable methodology known to one of skill in the artand with the help of this disclosure, such as ion-exchange, incipientwetness, spray drying, pore fill, aqueous impregnation, or the like.

In an aspect, contacting of the silica support (e.g., the hydratedsilica support, the dried silica support), the titanated silica support,or the dried titanated silica support with the chromium-containingcompound can be effected by any suitable methodology known to one ofskill in the art and with the help of this disclosure, such asion-exchange, incipient wetness, spray drying, pore fill, aqueousimpregnation, organic solvent impregnation, melt coating, or the like.

In an aspect, contacting of the silica support (e.g., the hydratedsilica support, the dried silica support) with the titanium-containingsolution (e.g., ATS) that further comprises a chromium-containingcompound can be effected by any suitable methodology known to one ofskill in the art and with the help of this disclosure, such asion-exchange, incipient wetness, spray drying, pore fill, aqueousimpregnation, or the like.

In some aspects of the present disclosure, contacting of the componentsutilized in preparation of the olefin polymerization catalyst may becarried out in the presence of a reaction media. In a further aspect,the reaction media may be formed during contacting of the componentsutilized in preparation of the olefin polymerization catalyst. Thereaction media can comprise a solvent (e.g., water) as disclosed hereinand one or more liquids associated with the components utilized inpreparation of the olefin polymerization catalyst (e.g., waterassociated with the silica support, water associated with thecarboxylate (e.g, carboxylic acid), water associated with achromium-containing compound). In an aspect, the reaction media excludesany solid component utilized in the preparation of the olefinpolymerization catalyst disclosed herein (e.g., silica support and anysolids associated therewith). In some aspects, a sum of an amount ofwater present in the reaction media may be in a range of from about 1wt. % to about 99 wt. %; alternatively, from about 1 wt. % to about 50wt. %; alternatively, from about 1 wt. % to about 20 wt. %; oralternatively, from about 1 wt. % to about 10 wt. % based upon the totalweight of the reaction media. In yet a further aspect, the reactionmedia may contain greater than about 20 wt. % water; alternatively,about 40 wt. % water; alternatively, about 60 wt. % water;alternatively, about 80 wt. % water; or alternatively, about 90 wt. %water based upon the total weight of the reaction media wherein thewater may originate from one or more components utilized in preparationof the olefin polymerization catalyst.

Drying the titanated support, the chrominated support (e.g., Cr-silicasupport) and/or the chrominated, titanated support can be effected byany means known to one of skill in the art and with the help of thisdisclosure. For example, drying can comprise heating the support to atemperature in a range of from about 25° C. to about 300° C.;alternatively, from about 50° C. to about 150° C.; or alternatively,from about 75° C. to about 100° C. Drying can further comprisemaintaining the temperature in the range of from about 25° C. to about300° C.; alternatively, from about 50° C. to about 150° C.; oralternatively, from about 75° C. to about 100° C. for a time period offrom about 0.01 minutes to about 6 hours, alternatively from about 30minutes to about 6 hours to form a dried support (e.g., which can, inaspects be the pre-catalyst composition). In aspects, for example,drying can be optionally used to remove solvent introduced by theaddition of the titanium-containing compound and/or thechromium-containing compound and/or the presence of a reaction media. Adried chrominated, titanated support may be referred to as apre-catalyst that is suitable for activation (e.g., via calcining) tobecome a catalyst (e.g., an olefin polymerization catalyst).

In an aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst further comprises activating apre-catalyst composition prepared as disclosed herein via a calcinationstep. In some aspects, calcination of the pre-catalyst compositioncomprises heating the pre-catalyst composition in an oxidizingenvironment to produce the olefin polymerization catalyst. For example,the pre-catalyst composition may be calcined by heating the pre-catalystcomposition in the presence of air to a temperature in a range of fromabout 400° C. to about 1000° C.; alternatively, from about 500° C. toabout 900° C.; or alternatively, from about 500° C. to about 850° C.Calcination of the pre-catalyst composition may further comprisemaintaining the temperature of the pre-catalyst composition in thepresence of air in the range of from about 400° C. to about 1000° C.;alternatively, from about 500° C. to about 900° C.; or alternatively,from about 500° C. to about 850° C. for a time period in a range of fromabout 1 minute to about 24 hours; alternatively, from about 1 minute toabout 12 hours; alternatively, from about 20 minutes to about 12 hours;alternatively, from about 1 hour to about 10 hours; alternatively, fromabout 3 hours to about 10 hours; or alternatively, from about 3 hours toabout 5 hours to produce the olefin polymerization catalyst.

Also disclosed herein are a titanated silica support, a pre-catalystcomposition and a polymerization catalyst produced as described herein(e.g., products of the processes described herein). In an aspect,disclosed herein is a pre-catalyst comprising a silica support and (a)titanium in an amount ranging from about 0.01% to about 10% by totalweight of the pre-catalyst, wherein the titanium is present within asurface layer on the silica support; (b) a carboxylate (when present) inan amount ranging from about 5% to about 25% by total weight of thepre-catalyst; and (c) a surfactant in an amount ranging from about 2% toabout 20% by total weight of the pre-catalyst. In an aspect, thecarboxylate is provided by oxalic acid, citric acid, lactic acid,tartaric acid, gluconic acid, glycolic acid, or combinations thereof,and such carboxylate may be present and detectable in the pre-catalyst.In an aspect, the surfactant is selected from the group consisting ofnonionic and cationic, and such surfactant may be present and detectablein the pre-catalyst. In an aspect, the pre-catalyst further comprises(d) chromium in an amount ranging from about 0.01% to about 10% by totalweight of the pre-catalyst. In an aspect, the silica support comprises asurface area of from about 100 m²/gram to about 1000 m²/gram and a porevolume of from about 1.0 cm³/gram to about 2.5 cm³/gram.

Further disclosed herein is a method of producing a polymer, and apolymer produced via the method. The method of producing a polymercomprises contacting a polymerization catalyst as described herein witha monomer under conditions suitable for formation of the polymer; andrecovering the polymer. In aspects, the monomer comprises ethylene andthe polymer comprises polyethylene.

The olefin polymerization catalysts of the present disclosure aresuitable for use in any olefin polymerization method, using varioustypes of polymerization reactors. In an aspect of the presentdisclosure, a polymer of the present disclosure is produced by anyolefin polymerization method, using various types of polymerizationreactors. As used herein, “polymerization reactor” includes any reactorcapable of polymerizing olefin monomers to produce homopolymers and/orcopolymers. Homopolymers and/or copolymers produced in the reactor maybe referred to as resin and/or polymers. The various types of reactorsinclude, but are not limited to those that may be referred to as batch,slurry, gas-phase, solution, high pressure, tubular, autoclave, or otherreactor and/or reactors. Gas phase reactors can comprise fluidized bedreactors or staged horizontal reactors. Slurry reactors can comprisevertical and/or horizontal loops. High pressure reactors can compriseautoclave and/or tubular reactors. Reactor types may include batchand/or continuous processes. Continuous processes may use intermittentand/or continuous product discharge or transfer. Processes may alsoinclude partial or full direct recycle of un-reacted monomer, un-reactedcomonomer, olefin polymerization catalyst and/or co-catalysts, diluents,and/or other materials of the polymerization process.

Polymerization reactor systems of the present disclosure can compriseone type of reactor in a system or multiple reactors of the same ordifferent type, operated in any suitable configuration. Production ofpolymers in multiple reactors may include several stages in at least twoseparate polymerization reactors interconnected by a transfer systemmaking it possible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. Alternatively,polymerization in multiple reactors may include the transfer, eithermanual or automatic, of polymer from one reactor to subsequent reactoror reactors for additional polymerization. Alternatively, multi-stage ormulti-step polymerization may take place in a single reactor, whereinthe conditions are changed such that a different polymerization reactiontakes place.

The desired polymerization conditions in one of the reactors may be thesame as or different from the operating conditions of any other reactorsinvolved in the overall process of producing the polymer of the presentdisclosure. Multiple reactor systems may include any combinationincluding, but not limited to, multiple loop reactors, multiple gasphase reactors, a combination of loop and gas phase reactors, multiplehigh pressure reactors, and a combination of high pressure with loopand/or gas reactors. The multiple reactors may be operated in series orin parallel. In an aspect of the present disclosure, any arrangementand/or any combination of reactors may be employed to produce thepolymer of the present disclosure.

According to one aspect of the present disclosure, the polymerizationreactor system can comprise at least one loop slurry reactor. Suchreactors are commonplace, and can comprise vertical or horizontal loops.Generally, continuous processes can comprise the continuous introductionof a monomer, an olefin polymerization catalyst, and/or a diluent into apolymerization reactor and the continuous removal from this reactor of asuspension comprising polymer particles and the diluent. Monomer,diluent, olefin polymerization catalyst, and optionally any comonomermay be continuously fed to a loop slurry reactor, where polymerizationoccurs. Reactor effluent may be flashed to remove the liquids thatcomprise the diluent from the solid polymer, monomer and/or comonomer.Various technologies may be used for this separation step, including butnot limited to, flashing that may include any combination of heataddition and pressure reduction; separation by cyclonic action in eithera cyclone or hydrocyclone; separation by centrifugation; or otherappropriate method of separation.

Typical slurry polymerization processes (also known as particle-formprocesses) are disclosed in U.S. Pat. Nos. 3,248,179, 4,501,885,5,565,175, 5,575,979, 6,239,235, 6,262,191 and 6,833,415, for example;each of which are herein incorporated by reference in their entirety.

Diluents suitable for use in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is the polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another aspect of the present disclosure, thepolymerization reactor can comprise at least one gas phase reactor. Suchsystems may employ a continuous recycle stream containing one or moremonomers continuously cycled through a fluidized bed in the presence ofthe olefin polymerization catalyst under polymerization conditions. Arecycle stream may be withdrawn from the fluidized bed and recycled backinto the reactor. Simultaneously, polymer product may be withdrawn fromthe reactor and new or fresh monomer may be added to replace thepolymerized monomer. Such gas phase reactors can comprise a process formulti-step gas-phase polymerization of olefins, in which olefins arepolymerized in the gaseous phase in at least two independent gas-phasepolymerization zones while feeding an olefin polymerizationcatalyst-containing polymer formed in a first polymerization zone to asecond polymerization zone. One type of gas phase reactor suitable foruse is disclosed in U.S. Pat. Nos. 4,588,790, 5,352,749, and 5,436,304,each of which is incorporated by reference in its entirety herein.

According to still another aspect of the present disclosure, ahigh-pressure polymerization reactor can comprise a tubular reactor oran autoclave reactor. Tubular reactors may have several zones wherefresh monomer, initiators, or olefin polymerization catalysts are added.Monomer may be entrained in an inert gaseous stream and introduced atone zone of the reactor. Initiators, olefin polymerization catalysts,and/or catalyst components may be entrained in a gaseous stream andintroduced at another zone of the reactor. The gas streams may beintermixed for polymerization. Heat and pressure may be employedappropriately to obtain optimal polymerization reaction conditions.

According to yet another aspect of the present disclosure, thepolymerization reactor can comprise a solution polymerization reactorwherein the monomer is contacted with the olefin polymerization catalystcomposition by suitable stirring or other means. A carrier comprising anorganic diluent or excess monomer may be employed. If desired, themonomer may be brought in the vapor phase and into contact with thecatalytic reaction product, in the presence or absence of liquidmaterial. The polymerization zone is maintained at temperatures andpressures that will result in the formation of a solution of the polymerin a reaction medium. Agitation may be employed to obtain bettertemperature control and to maintain uniform polymerization mixturesthroughout the polymerization zone. Adequate means are utilized fordissipating the exothermic heat of polymerization.

Polymerization reactors suitable for use in the present disclosure mayfurther comprise any combination of at least one raw material feedsystem, at least one feed system for an olefin polymerization catalystor catalyst components, and/or at least one polymer recovery system.Suitable reactor systems for the present disclosure may further comprisesystems for feedstock purification, catalyst storage and preparation,extrusion, reactor cooling, polymer recovery, fractionation, recycle,storage, loadout, laboratory analysis, and process control.

Conditions that are controlled for polymerization efficiency and toprovide polymer properties include, but are not limited to, temperature,pressure, type and quantity of the olefin polymerization catalyst orco-catalyst, and the concentrations of various reactants. Polymerizationtemperature can affect catalyst productivity, polymer molecular weightand molecular weight distribution. Suitable polymerization temperaturesmay be any temperature below the de-polymerization temperature,according to the Gibbs Free Energy Equation. Typically, this includesfrom about 60° C. to about 280° C., for example, and/or from about 70°C. to about 110° C., depending upon the type of polymerization reactorand/or polymerization process.

Suitable pressures will also vary according to the reactor andpolymerization process. The pressure for liquid phase polymerization ina loop reactor is typically less than 1000 psig (6.9 MPa). Pressure forgas phase polymerization is usually in a range of from about 200 psig(1.4 MPa)-500 psig (3.45 MPa). High-pressure polymerization in tubularor autoclave reactors is generally run in a range of from about 20,000psig (138 MPa) to 75,000 psig (518 MPa). Polymerization reactors canalso be operated in a supercritical region occurring at generally highertemperatures and pressures. Operation at conditions above the criticalpoint as indicated by a pressure/temperature diagram (supercriticalphase) may offer advantages.

The concentration of various reactants can be controlled to producepolymers with certain physical and mechanical properties. The proposedend-use product that will be formed by the polymer and the method offorming that product may be varied to determine the desired finalproduct properties. Mechanical properties include, but are not limitedto tensile strength, flexural modulus, impact resistance, creep, stressrelaxation and hardness test values. Physical properties include, butare not limited to density, molecular weight, molecular weightdistribution, melting temperature, glass transition temperature,temperature melt of crystallization, density, stereoregularity, crackgrowth, short chain branching, long chain branching and rheologicalmeasurements.

The concentrations of monomer, comonomer, hydrogen, co-catalyst,modifiers, and electron donors are generally important in producingspecific polymer properties. Comonomer may be used to control productdensity. Hydrogen may be used to control product molecular weight.Co-catalysts may be used to alkylate, scavenge poisons and/or controlmolecular weight. The concentration of poisons may be minimized, aspoisons may impact the reactions and/or otherwise affect polymer productproperties. Modifiers may be used to control product properties andelectron donors may affect stereoregularity.

Polymers such as polyethylene homopolymers and copolymers of ethylenewith other mono-olefins may be produced in the manner described aboveusing the olefin polymerization catalysts prepared as described herein.Polymers produced as disclosed herein may be formed into articles ofmanufacture or end use articles using techniques known in the art suchas extrusion, blow molding, injection molding, fiber spinning,thermoforming, and casting. For example, a polymer resin may be extrudedinto a sheet, which is then thermoformed into an end use article such asa container, a cup, a tray, a pallet, a toy, or a component of anotherproduct. Examples of other end use articles into which the polymerresins may be formed include pipes, films, and bottles.

A method of the present disclosure comprises contacting an olefinpolymerization catalyst of the type described with an olefin monomerunder conditions suitable for the formation of a polyolefin andrecovering the polyolefin. In an aspect the olefin monomer is anethylene monomer and the polyolefin is an ethylene polymer(polyethylene).

Polyethylene prepared as described herein may be characterized by a highload melt index (HLMI), in a range of from about 1 g/10 min. to about1000 g/10 min.; alternatively, from about 3 g/10 min. to about 300 g/10min.; alternatively, from about 6 g/10 min. to about 100 g/10 min.; oralternatively, from about 15 g/10 min. to about 40 g/10 min.

The melt index (MI) represents the rate of flow of a molten polymerthrough an orifice of 0.0825 inch diameter when subjected to a force of2,160 grams at 190° C. as determined in accordance with ASTM D1238-82condition E. The 110 represents the rate of flow of a molten polymerthrough an orifice of 0.0825 inch diameter when subjected to a force of10,000 grams at 190° C. as determined in accordance with ASTM D1238-82condition N. The HLMI (high load melt index) represents the rate of flowof a molten polymer through an orifice of 0.0825 inch diameter whensubjected to a force of 21,600 grams at 190° C. as determined inaccordance with ASTM D1238-82 condition F.

Utilization of an titanium-containing solution (e.g., ATS) in thepreparation of an olefin polymerization catalyst of the presentdisclosure may be advantageous because the ATS can facilitate theassociation of titanium with a silica support in the presence of anaqueous solvent (e.g., water). Further advantages may occur when thetitanium-containing solution utilized to form the olefin polymerizationcatalyst comprises an aqueous solvent (e.g., water). The solubility oftitanium in the aqueous solvent may be sufficient to allow the use ofspray drying methodologies for contacting the ATS and a silica support.Spray drying as used herein refers to a method of producing a dry powderfrom a liquid or slurry by rapidly drying with a hot gas. Spray dryingmethodologies may be utilized in the preparation of olefinpolymerization catalysts in a continuous production method with thepotential to produce large volumes of olefin polymerization catalysts.Spray drying methodologies may also be utilized in the preparation ofolefin polymerization catalysts having a consistent particle sizedistribution.

Utilization of the titanium-containing solution comprising the aqueoussolvent (i.e., ATS) may permit use of a hydrated silica support andobviate the thermal treatment required for anhydrous methods of catalystpreparation, (e.g., drying a hydrated silica support prior to contactwith any other catalyst component).

Utilizing surfactants as a chelating agent, as described herein,provides a cheap, effective way of preventing hydrolysis of the titaniumduring aqueous titanation.

The herein disclosed utilization of surfactants as ligands for titanium,that are soluble in water but resist hydrolysis, enables binding of thetitanium to a support during the production of chromium-silica-titanium(Cr/Si—Ti) catalyst. Aqueous solutions of ligands, as described herein,which are inexpensive, can be utilized in the aqueous titanation ofpolymerization catalysts.

Highly reactive volatile organic compounds (HRVOC) may be emitted duringcatalyst production. HRVOCs play a role in the formation of ozone inozone nonattainment areas, i.e., areas that do not meet theEnvironmental Protection Agency's air quality standards for ground-levelozone. Consequently, processes that create HRVOC emissions may besubject to compliance with various state and federal regulationsregarding HRVOC emission, such as the HRVOC emissions cap and tradeprogram. Utilization of an aqueous titanium solution (ATS) to produce apre-catalyst composition and a polymerization catalyst as describedherein can results in the production of a reduced amount of HRVOCsduring catalyst production, e.g., due to the use of the aqueoussolution, rather than an organic solvent. The herein disclosed methodprovides an inexpensive, effective and efficient way of producing anolefin polymerization catalyst.

EXAMPLES

The following examples are given as particular aspects of the presentdisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification or the claims to follow in anymanner.

In each experiment of the following examples HA30W, a Cr/silica catalystmade by W. R Grace, was titanated as described below and activated bycalcination at 650° C. in air for three hours. The final catalystscontained 3.5 wt % titanium.

Activity tests were conducted in a 2.2 liter steel reactor equipped witha marine stirrer running at 400 rpm. The reactor was surrounded by asteel jacket circulating water, the temperature of which was controlledby use of steam and water heat exchangers. These were connected in anelectronic feed-back loop so that the reactor temperature could bemaintained at +/−0.5° C. during the reaction.

Unless otherwise stated, a small amount (0.01 to 0.10 grams normally) ofthe solid chromium catalyst was first charged under nitrogen to the dryreactor. Next about 0.25 g of sulfate-treated alumina (600° C.) wasadded as a scavenger for poisons. Then 1.2 liter of isobutane liquid wascharged and the reactor heated up to the specified temperature, usually105° C. Finally, ethylene was added to the reactor to equal a fixedpressure, normally 550 psig (3.8 MPa), which was maintained during theexperiment. The stirring was allowed to continue for the specified time,usually around one hour, and the activity was noted by recording theflow of ethylene into the reactor to maintain the set pressure.

After the allotted time, the ethylene flow was stopped and the reactorslowly depressurized and opened to recover a granular polymer powder. Inall cases the reactor was clean with no indication of any wall scale,coating or other forms of fouling. The polymer powder was then removedand weighed. Activity was specified as grams of polymer produced pergram of solid catalyst charged per hour.

Comparative Example 1

Experiments were performed in which 30 g of HA30W catalyst wasimpregnated with an aqueous solution of titanium (3.5 wt % titanium loadon catalyst). First, to 50 mL of water was added 3.94 g of anhydrousoxalic acid (2 moles of oxalic acid per mole of titanium). It dissolvedafter a few minutes of stirring. Then freshly precipitated hydroustitania was prepared by adding 6.7 mL of titanium isopropoxide to theoxalic acid solution. After a few minutes of stirring the titaniadissolved in the oxalic acid solution. Then 5 mL % of varioussurfactants (noted in Table 1) was added. After a few minutes ofstirring, the resultant solution was added to the HA30W catalyst. Afterbeing stirred a few times, it formed a damp solid powder, which was thendried in a vacuum oven at 100° C. for typically 12 hours. Afterward, asample of the catalyst was calcined by fluidization in dry air at 650°C. for three hours. Polymerization was carried out as described above,at 105° C., in isobutane and with 550 psig (3.8 MPa) ethylene pressure.

Two control runs, C1 and C2, were performed. Control run C1 shows theresults of the base Cr/silica support, containing no titanium compoundor surfactant. As seen in Table 1, the melt index obtained from thepolymer produced in example C1 is low. Control run C2 shows theimpregnation of titanium (at 3.5 wt %) and oxalic acid, but withoutsurfactant. In other words, control catalyst 2 was made exactly as theinventive catalysts were made, except with the omission of thesurfactant. When activated and tested in a polymerization run under thesame conditions, it produced polymer. However, notice again that themelt index of the polymer made by catalyst C2 is still equally low,indicating that the titanation is completely ineffective.

In inventive runs I1-I8, the exact same procedure was employed, exceptfor the addition of 5 mL of various surfactants, as noted in Table 1. Itis noted that in every inventive run the melt index was increasedrelative to control runs C1 and C2. Inventive runs I5 and I6 were takento higher productivity (yield) which tends to lower melt index.Therefore, in these runs, the catalyst also exhibited a significantlyimproved melt index potential, even though the observed melt index inthese two runs was lower than the other inventive runs. However, noticethat this is confirmed in the next inventive run, I7, where the samecatalyst as used in I6 was tested again but at a lower productivity, andthe melt index came up significantly, to above 12, which is also higherthan the two control runs C1 and C2.

Table 1 shows the components utilized in the control and inventiveexperiments, and also provides the yield (grams polyethylene per gramcatalyst), the activity (grams polyethylene per gram catalyst per hour),the high load melt index (HLMI, in decigrams per minute, as measured byASTM D1238, condition 190/21.6, at 190° C. with a 21.6 kg weight), the110 (also in decigrams per minute, and measured in the same way but witha 10 kg weight), the melt index (MI, decigrams per minute, as measuredby ASTM D1238, condition 190/2.16, at 190° C. with a 2.16 kg weight),and the shear (ratio of the HLMI to the MI).

TABLE 1 Ti Yield Activity HLMI I10 MI Run (wt %) Surfactant (g/g)(g/g-h) (dg/min) (dg/min) (dg/min) Control Runs: C1 0 None 2973 2973 5.50.87 0.000 C2 3.5 None 2933 3088 6.4 1.03 — Inventive Runs: I1 3.5Pluronic 25 R-2 2514 3143 12.2 2.28 — I2 3.5 Pluronic 10 R-5 2132 312011.0 2.04 0.41 I3 3.5 Surfynol 465 2970 3073 10.7 1.98 0.44 I4 3.5Surfynol 61 Insoluble — — — — I5 3.5 Surfynol 2502 3377 5476 6.9 1.050.000 I6 3.5 Dow DS-1000 3325 6235 5.6 0.89 0.000 I7 3.5 Dow DS-10002029 2387 12.3 2.32 0.049 I8 3.5 Surfynols 465 1973 4082 17.2 3.24 0.093& 61

The experimental results show that an aqueous titanium solution (ATS)comprising a surfactant as described herein can be utilized tosuccessfully titanate a polymerization catalyst. Without intending to belimited by theory, it is believed that the presence of a surfactant ofthe type described herein helps to prevent undesired “clumping” oragglomeration of the titanium on the silica support during the dryingand/or calcination steps. The clumped or agglomerated forms of titaniumon the silica support do not provide a desired catalytic function incontrast to a dispersed form of titanium on the silica support that doesprovide a desired catalytic function and resultant polymercharacteristics (e.g., increased melt index). Without intending to belimited by theory, it is believed that the surfactant may function as aligand to prevent degradation (e.g., hydrolysis) of one or moreintermediate titanium compounds (e.g., titanium oxalate) formed duringthe catalyst preparation methodology (e.g., formation of the ATS,impregnation of the silica support with the ATS, drying the impregnatedsupport, and/or calcining the dried impregnated support to yield aCr/Si—Ti catalyst).

ADDITIONAL DISCLOSURE

The following enumerated aspects of the present disclosure are providedas non-limiting examples.

A first aspect which is a method comprising contacting a silica supportwith a titanium-containing solution to form a titanated silica support,wherein the titanium-containing solution comprises a titanium compound,a solvent, and a surfactant.

A second aspect which is the method of the first aspect, furthercomprising drying the titanated silica support by heating the titanatedsilica support to a temperature in a range of from about 50° C. to about200° C. and maintaining the temperature of the titanated silica supportin the range of from about 50° C. to about 200° C. for a time period offrom about 0.01 minutes to about 6 hours to form a pre-catalyst.

A third aspect which is the method of the second aspect, furthercomprising contacting a chromium-containing compound with the silicasupport, the titanated silica support, the pre-catalyst, or combinationsthereof.

A fourth aspect which is the method of the first or the second aspect,wherein the silica support comprises chromium.

A fifth aspect which is the method of the first or the second aspect,wherein the silica support is simultaneously contacted with thetitanium-containing solution and a chromium-containing compound.

A sixth aspect which is the method of the fifth aspect, wherein thetitanium-containing solution comprises the chromium-containing compound.

A seventh aspect which is the method of the third, the fifth or thesixth aspect, wherein the chromium-containing compound compriseschromium trioxide, chromium acetate, chromium nitrate, chromium sulfate,tertiary butyl chromate, biscyclopentadienyl chromium(II), chromium(III)acetylacetonate, or combinations thereof.

An eighth aspect which is the method of any of the first through theseventh aspects, wherein the solvent is selected from the groupconsisting of water, alcohol, and combinations thereof.

A ninth aspect which is the method of any of the first through theseventh aspects, wherein the solvent is an aqueous solvent.

A tenth aspect which is the method of the first aspect, wherein thesilica support is a hydrogel or xerogel that contains no titanium priorto contact with the titanium-containing solution.

An eleventh aspect which is the method of any of the first through thetenth aspects, wherein the titanium compound comprises a titanium (IV)compound, a titanium (III) compound, titania, or combinations thereof.

A twelfth aspect which is the method of the eleventh aspect, wherein thetitanium compound comprises a titanium(IV) compound comprising analkoxide group.

A thirteenth aspect which is the method of the twelfth aspect, whereinthe titanium compound has the formula Ti(OR)₄, TiO(OR)₂, Ti(OR)₂(acac)₂,or Ti(OR)₂(oxal), wherein “acac” is acetylacetonate, “oxal” is oxalate,and each R independently is ethyl, isopropyl, n-propyl, isobutyl, orn-butyl.

A fourteenth aspect which is the method of the eleventh aspect, whereinthe titanium (IV) compound comprises Ti(OH)₄, TiO(OH)₂, TiO₂,TiO(oxalate)₂, or a combination thereof, and wherein the titanium (III)compound comprises Ti₂(SO₄)₃, Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, or acombination thereof.

A fifteenth aspect which is the method of any of the first through thefourteenth aspects, wherein the titanium-containing solution furthercomprises a carboxylate.

A sixteenth aspect which is the method of the fifteenth aspect, whereinthe carboxylate comprises a multi carboxylate, an alpha-hydroxycarboxylate, or a combination thereof

A seventeenth aspect which is the method of the fifteenth aspect,wherein the carboxylate is provided by oxalic acid, citric acid, lacticacid, tartaric acid, gluconic acid, glycolic acid, malonic acid, orcombinations thereof.

An eighteenth aspect which is the method of the fifteenth, sixteenth orseventeenth aspect, wherein the aqueous titanium solution comprises anequivalent molar ratio of the carboxylate to the titanium compound in arange of from about 1 to about 4, or greater than or equal to about 1,2, 3, or 4.

A nineteenth aspect which is the method of the twelfth aspect, whereinthe titanium-containing solution further comprises a carboxylate,wherein the carboxylate is provided by oxalic acid, citric acid, lacticacid, tartaric acid, gluconic acid, glycolic acid, malonic acid, orcombinations thereof.

A twentieth aspect which is the method of any of the first through thenineteenth aspects, wherein the surfactant comprises a non-ionicsurfactant, a cationic surfactant, or combinations thereof.

A twenty-first aspect which is the method of any of the first throughthe twentieth aspects, wherein the titanium-containing solutioncomprises from about 1% to about 25%, from about 2% to about 20%, orfrom about 3% to about 10% of the surfactant, based on the weight of thesurfactant and the weight of the titanium solution.

A twenty-second aspect which is the method of any one of the firstthrough the twenty-first aspects, wherein the silica support has asurface area of from about 100 m²/gram to about 1000 m²/gram and a porevolume of from about 1.0 cm³/gram to about 2.5 cm³/gram.

A twenty-third aspect which is the method of any of the third throughthe twenty-second aspects, further comprising calcining the pre-catalystby heating the pre-catalyst in a reducing atmosphere to a temperature ina range of from about 400° C. to about 1000° C. and maintaining thetemperature of the pre-catalyst in the range of from about 400° C. toabout 1000° C. for a time period of from about 1 minute to about 24hours to form a catalyst.

A twenty-fourth aspect which a method comprising contacting achrominated silica support with an aqueous titanium solution to form atitanated, chrominated silica support, wherein the aqueous titaniumsolution comprises water, a titanium compound, a carboxylic acid, and asurfactant, drying the chrominated, titanated silica support by heatingthe chrominated, titanated silica support to a temperature in a range offrom about 50° C. to about 200° C. and maintaining the temperature ofthe chrominated, titanated silica support in the range of from about 50°C. to about 200° C. for a time period of from about 1 second to about 6hours, alternatively from about 30 minutes to about 6 hours, to form apre-catalyst, and calcining the pre-catalyst by heating the pre-catalystin an oxidizing atmosphere (e.g., in the presence of oxygen) to atemperature in a range of from about 400° C. to about 1000° C. andmaintaining the temperature of the pre-catalyst in the range of fromabout 400° C. to about 1000° C. for a time period of from about 1 minuteto about 24 hours to form a catalyst.

A twenty-fifth aspect which is the method of the twenty-fourth aspect,wherein the aqueous titanium solution is prepared by any suitableaddition sequence (e.g., simultaneous or sequential), including by notlimited to (i) preparing a first solution by combining the carboxylicacid (e.g., oxalic acid, lactic acid, or malonic acid) and water; (ii)adding the titanium compound (e.g., titanium isopropoxide or TiO₂) tothe first solution to form a second solution, and (iii) adding thesurfactant to the second solution to form the aqueous titanium solution.

A twenty-sixth aspect which is the method of the twenty-fourth or thetwenty-fifth aspect, further comprising contacting a chromium-containingcompound with a silica support to form the chrominated silica support,wherein the chromium-containing compound comprises chromium trioxide,chromium acetate, chromium nitrate, chromium sulfate, tertiary butylchromate, biscyclopentadienyl chromium(II), chromium(III)acetylacetonate, or combinations thereof.

A twenty-seventh aspect which is a titanated silica support prepared bythe method of the first aspect.

A twenty-eighth aspect which is a pre-catalyst prepared by the method ofany of the third through the twenty-second aspects.

A twenty-ninth aspect which is a catalyst produced by the method of thetwenty-third, the twenty-fourth, the twenty-fifth or the twenty-sixthaspect.

A thirtieth aspect which is the pre-catalyst of the twenty-eighthaspect, wherein an amount of titanium present in the pre-catalyst rangesfrom about 0.01% to about 10% by total weight of the pre-catalyst and anamount of chromium present in the pre-catalyst ranges from about 0.01%to about 10% by total weight of the pre-catalyst.

A thirty-first aspect which is the catalyst of the twenty-ninth aspect,wherein an amount of titanium present in the catalyst ranges from about0.01% to about 10% by total weight of the catalyst and an amount ofchromium present in the catalyst ranges from about 0.01% to about 10% bytotal weight of the catalyst.

A thirty-second aspect which is a pre-catalyst comprising a silicasupport and (a) titanium in an amount ranging from about 0.01% to about10% by total weight of the pre-catalyst, wherein the titanium is presentwithin a surface layer on the silica support, (b) a carboxylate in anamount ranging from about 5% to about 25% by total weight of thepre-catalyst, and (c) a surfactant in an amount ranging from about 2% toabout 20% by total weight of the pre-catalyst.

A thirty-third aspect which is the pre-catalyst of the thirty-secondaspect, wherein the carboxylate is provided by oxalic acid, citric acid,lactic acid, tartaric acid, gluconic acid, glycolic acid, orcombinations thereof.

A thirty-fourth aspect which is the pre-catalyst of the thirty-second orthe thirty-third aspect, wherein the surfactant is selected from thegroup consisting of nonionic and cationic.

A thirty-fifth aspect which is the pre-catalyst of the thirty-second,thirty-third, or thirty-fourth aspect, further comprising (d) chromiumin an amount ranging from about 0.01% to about 10% by total weight ofthe pre-catalyst.

A thirty-sixth aspect which is the pre-catalyst of the thirty-second,thirty-third, thirty-fourth or the thirty-fifth aspect, wherein thesilica support comprises a surface area of from about 100 m²/gram toabout 1000 m²/gram and a pore volume of from about 1.0 cm³/gram to about2.5 cM³/gram.

A thirty-seventh aspect which is the method of any of the first throughthe twenty-third aspects, wherein the silica support is selected fromthe group consisting of a silica xerogel, a silica hydrogel, solidsilica (e.g., crystalline silicon dioxide), solid silica-alumina, andcombinations thereof.

A thirty-eighth aspect which is a method comprising dissolving atitanium compound in an aqueous solution comprising a carboxylate and asurfactant to form an aqueous titanium solution, wherein the carboxylatecomprises a multi carboxylate, an alpha-hydroxy carboxylate, or acombination thereof; forming a titanated silica support by contacting asilica support with the aqueous titanium solution to form the titanatedsupport; drying the titanated support by heating the titanated supportto a temperature in a range of from about 50° C. to about 200° C. andmaintaining the temperature of the titanated support in the range offrom about 50° C. to about 200° C. for a time period of from about 0.01minutes to about 6 hours to form a dried titanated support; andcalcining the dried titanated support by heating the dried titanatedsupport to a temperature in a range of from about 400° C. to about 1000°C. and maintaining the temperature of the dried titanated support in therange of from about 400° C. to about 1000° C. for a time period of fromabout 1 minute to about 24 hours to form a catalyst, wherein thecatalyst further comprises chromium incorporated therein via contactingof a chromium-containing compound with the silica support, the titanatedsupport, the dried titanated support, or a combination thereof.

A thirty-ninth aspect which is the method of the thirty-eighth aspect,wherein the titanium compound is a titanium (IV) compound selected fromthe group consisting of Ti(OH)₄, TiO(OH)₂, TiO₂, TiO(oxalate)₂, andcombinations thereof, or a titanium (III) compound selected from thegroup consisting of Ti₂(SO₄)₃, Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, andcombinations thereof; and wherein the carboxylate is provided by oxalicacid, citric acid, lactic acid, tartaric acid, gluconic acid, glycolicacid, malonic acid, or a combination thereof.

A fortieth aspect which is a method of forming a pre-catalystcomposition, the method comprising forming a titanated silica supportvia the use of an aqueous titanium solution formed by dissolving atitanium compound in an aqueous solution comprising a carboxylate and asurfactant, wherein the carboxylate comprises a multi-carboxylate, analpha-hydroxy carboxylate, or a combination thereof and drying thetitanated support by heating the titanated support to a temperature in arange of from about 50° C. to about 200° C. and maintaining thetemperature of the titanated support in the range of from about 50° C.to about 200° C. for a time period of from about 30 minutes to about 6hours to form a dried titanated support; and wherein chromium is addedvia contacting (i) a silica support contacted with the aqueous titaniumsolution to form the titanated support, (ii) the titanated support,(iii) the dried titanated support, or (iv) a combination thereof with achromium-containing compound to form the pre-catalyst composition.

A forty-first aspect which is the method of the fortieth aspect, whereinthe titanium compound is a titanium (IV) compound selected from thegroup consisting of Ti(OH)₄, TiO(OH)₂, TiO₂, TiO(oxalate)₂, andcombinations thereof, or a titanium (III) compound selected from thegroup consisting of Ti₂(SO₄)₃, Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, andcombinations thereof; and wherein the carboxylate is provided by oxalicacid, citric acid, lactic acid, tartaric acid, gluconic acid, glycolicacid, malonic acid, or a combination thereof.

A forty-second aspect which is a method of producing polyethylene,comprising contacting the catalyst of the twenty-ninth aspect withethylene under conditions suitable for formation of polyethylene; andrecovering the polyethylene.

The terms “a”, “an”, and “the” are intended, unless specificallyindicated otherwise, to include plural alternatives, e.g., at least one.Herein, while methods and processes are described in terms of“comprising” various components or steps, the methods and processes canalso “consist essentially of” or “consist of” the various components orsteps. A particular feature of the disclosed subject matter can bedisclosed as follows: Feature X can be A, B, or C. It is alsocontemplated that for each feature the statement can also be phrased asa listing of alternatives such that the statement “Feature X is A,alternatively B, or alternatively C” is also an aspect of the presentdisclosure whether or not the statement is explicitly recited.

While various aspects of the present disclosure have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the presentdisclosure. The aspects of the present disclosure described herein areexemplary only and are not intended to be limiting. Many variations andmodifications of the present disclosure are possible and are within thescope of the present disclosure. Where numerical ranges or limitationsare expressly stated, such express ranges or limitations should beunderstood to include iterative ranges or limitations of like magnitudefalling within the expressly stated ranges or limitations (e.g., “fromabout 1 to about 10” includes, 2, 3, 4, etc.; “greater than 0.10”includes 0.11, 0.12, 0.13, etc.). Use of the term “optionally” withrespect to any element of a claim is intended to mean that the subjectelement is required, or alternatively, is not required. Bothalternatives are intended to be within the scope of the claim. Use ofbroader terms such as “comprises”, “includes”, “having”, etc. should beunderstood to provide support for narrower terms such as “consistingof”, “consisting essentially of”, “comprised substantially of”, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an aspect of thepresent disclosure. Thus, the claims are a further description and arean addition to the aspect of the present disclosure. The discussion of areference in the present disclosure is not an admission that it is priorart to the present disclosure, especially any reference that may have apublication date after the priority date of this application. Thepresent disclosures of all patents, patent applications, andpublications cited herein are hereby incorporated by reference, to theextent that they provide exemplary, procedural or other detailssupplementary to those set forth herein.

All publications, patent applications, and patents mentioned herein areincorporated by reference in their entirety. In the event of conflict,the present specification, including definitions, is intended tocontrol. With respect to all ranges disclosed herein, such ranges areintended to include any combination of the mentioned upper and lowerlimits even if the particular combination is not specifically listed.

What is claimed is:
 1. A method consisting of contacting a silica support with a titanium-containing solution to form a titanated silica support, wherein the titanium-containing solution consists of a titanium compound, a solvent, a carboxylate, and a surfactant, wherein the titanium-containing solution has a pH of less than about 5.5, wherein the surfactant comprises a water-insoluble component and a water-soluble component, wherein the titanium-containing solution comprises from about 5 wt. % to about 15 wt. % of the surfactant, based on weight of the surfactant and weight of the titanium, and wherein the aqueous titanium solution comprises an equivalent molar ratio of the carboxylate to the titanium compound in a range of from about 1 to about
 4. 2. The method of claim 1, further comprising drying the titanated silica support by heating the titanated silica support to a temperature in a range of from about 50° C. to about 200° C. and maintaining the temperature of the titanated silica support in the range of from about 50° C. to about 200° C. for a time period of from about 0.01 minutes to about 6 hours to form a pre-catalyst.
 3. The method of claim 2, further comprising contacting a chromium-containing compound with the silica support, the titanated silica support, the pre-catalyst, or combinations thereof.
 4. The method of claim 1, wherein the silica support comprises chromium.
 5. The method of claim 1, wherein the silica support is simultaneously contacted with the titanium-containing solution and a chromium-containing compound.
 6. The method of claim 3, wherein the chromium-containing compound comprises chromium trioxide, chromium acetate, chromium nitrate, chromium sulfate, tertiary butyl chromate, biscyclopentadienyl chromium(II), chromium(III) acetylacetonate, or combinations thereof.
 7. The method of claim 1, wherein the solvent is selected from the group consisting of water, alcohol, and combinations thereof.
 8. The method of claim 1, wherein the solvent is an aqueous solvent.
 9. The method of claim 1, wherein the silica support is a hydrogel or xerogel that contains no titanium prior to contact with the titanium-containing solution.
 10. The method of claim 1, wherein the titanium compound comprises a titanium (IV) compound, a titanium (III) compound, titania, or combinations thereof.
 11. The method of claim 10, wherein the titanium compound comprises a titanium(IV) compound comprising an alkoxide group.
 12. The method of claim 11, wherein the titanium compound has the formula Ti(OR)₄, TiO(OR)₂, Ti(OR)₂(acac)₂, or Ti(OR)₂(oxal), wherein “acac” is acetylacetonate, “oxal” is oxalate, and each R independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl.
 13. The method of claim 10, wherein the titanium (IV) compound comprises Ti(OH)₄, TiO(OH)₂, TiO₂, TiO(oxalate)₂, or a combination thereof, and wherein the titanium (III) compound comprises Ti₂(SO₄)₃, Ti(OAc)₃, Ti(oxalate)₃, Ti(NO₃)₃, or a combination thereof.
 14. The method of claim 1, wherein the carboxylate comprises a multi carboxylate, an alpha-hydroxy carboxylate, or a combination thereof.
 15. The method of claim 1, wherein the carboxylate is provided by a carboxylic acid selected from the group consisting of acetic acid, formic acid, citric acid, gluconic acid, glycolic acid, glyoxylic acid, lactic acid, malic acid, malonic acid, oxalic acid, propionic acid, phosphonoacetic acid, tartaric acid, and combinations thereof.
 16. The method of claim 11, wherein the titanium-containing solution further comprises a carboxylate, wherein the carboxylate is provided a carboxylic acid selected from the group consisting of acetic acid, formic acid, citric acid, gluconic acid, glycolic acid, glyoxylic acid, lactic acid, malic acid, malonic acid, oxalic acid, propionic acid, phosphonoacetic acid, tartaric acid, and combinations thereof.
 17. The method of claim 1, wherein the surfactant comprises a non-ionic surfactant, a cationic surfactant, or combinations thereof.
 18. The method of claim 1, wherein the titanium compound is a titanium (IV) compound. 